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  1. //===- LineIterator.h - Iterator to read a text buffer's lines --*- C++ -*-===//
  2. //
  3. // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
  4. // See https://llvm.org/LICENSE.txt for license information.
  5. // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
  6. //
  7. //===----------------------------------------------------------------------===//
  8.  
  9. #ifndef LLVM_SUPPORT_LINEITERATOR_H
  10. #define LLVM_SUPPORT_LINEITERATOR_H
  11.  
  12. #include "llvm/ADT/StringRef.h"
  13. #include "llvm/Support/DataTypes.h"
  14. #include "llvm/Support/MemoryBufferRef.h"
  15. #include <iterator>
  16. #include <optional>
  17.  
  18. namespace llvm {
  19.  
  20. class MemoryBuffer;
  21.  
  22. /// A forward iterator which reads text lines from a buffer.
  23. ///
  24. /// This class provides a forward iterator interface for reading one line at
  25. /// a time from a buffer. When default constructed the iterator will be the
  26. /// "end" iterator.
  27. ///
  28. /// The iterator is aware of what line number it is currently processing. It
  29. /// strips blank lines by default, and comment lines given a comment-starting
  30. /// character.
  31. ///
  32. /// Note that this iterator requires the buffer to be nul terminated.
  33. class line_iterator {
  34.   std::optional<MemoryBufferRef> Buffer;
  35.   char CommentMarker = '\0';
  36.   bool SkipBlanks = true;
  37.  
  38.   unsigned LineNumber = 1;
  39.   StringRef CurrentLine;
  40.  
  41. public:
  42.   using iterator_category = std::forward_iterator_tag;
  43.   using value_type = StringRef;
  44.   using difference_type = std::ptrdiff_t;
  45.   using pointer = value_type *;
  46.   using reference = value_type &;
  47.  
  48.   /// Default construct an "end" iterator.
  49.   line_iterator() = default;
  50.  
  51.   /// Construct a new iterator around an unowned memory buffer.
  52.   explicit line_iterator(const MemoryBufferRef &Buffer, bool SkipBlanks = true,
  53.                          char CommentMarker = '\0');
  54.  
  55.   /// Construct a new iterator around some memory buffer.
  56.   explicit line_iterator(const MemoryBuffer &Buffer, bool SkipBlanks = true,
  57.                          char CommentMarker = '\0');
  58.  
  59.   /// Return true if we've reached EOF or are an "end" iterator.
  60.   bool is_at_eof() const { return !Buffer; }
  61.  
  62.   /// Return true if we're an "end" iterator or have reached EOF.
  63.   bool is_at_end() const { return is_at_eof(); }
  64.  
  65.   /// Return the current line number. May return any number at EOF.
  66.   int64_t line_number() const { return LineNumber; }
  67.  
  68.   /// Advance to the next (non-empty, non-comment) line.
  69.   line_iterator &operator++() {
  70.     advance();
  71.     return *this;
  72.   }
  73.   line_iterator operator++(int) {
  74.     line_iterator tmp(*this);
  75.     advance();
  76.     return tmp;
  77.   }
  78.  
  79.   /// Get the current line as a \c StringRef.
  80.   StringRef operator*() const { return CurrentLine; }
  81.   const StringRef *operator->() const { return &CurrentLine; }
  82.  
  83.   friend bool operator==(const line_iterator &LHS, const line_iterator &RHS) {
  84.     return LHS.Buffer == RHS.Buffer &&
  85.            LHS.CurrentLine.begin() == RHS.CurrentLine.begin();
  86.   }
  87.  
  88.   friend bool operator!=(const line_iterator &LHS, const line_iterator &RHS) {
  89.     return !(LHS == RHS);
  90.   }
  91.  
  92. private:
  93.   /// Advance the iterator to the next line.
  94.   void advance();
  95. };
  96. }
  97.  
  98. #endif
  99.